[Xenomai-help] Maximum number of kernel tasks?

[Xenomai-help] Maximum number of kernel tasks?

[Jefferson Noxon]

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Hello,

This is my first project using Xenomai. I have a Diamond Systems Athena II
board with an 800 MHz VIA Mark (Corefusion) chip. I built Xenomai 2.4.5 with
Linux kernel 2.6.26.5 and I-pipe 2.0-09.

For some reason I can create 7 kernel tasks just fine, but the 8th task
fails with -ENOMEM in rt_task_create(). I increased the heap size from 128Kb
to 256Kb, but the problem persists. If I remove my kernel module and re-load
it after a task creation fails, I get an oops in __xntimer_init after
starting my first task (which is periodic).

If I build the same code to run in user-space (I have ifdefs allowing me to
build it either way), I can create as many tasks as I want and my code
behaves exactly as I would expect it to.

I imagine I am probably doing something stupid, but since it works in user
mode I'm not sure what to check. Is there a limit of RT kernel tasks? If
not, any pointers on how to debug this would be appreciated.

Thanks

Jeff

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Re: [Xenomai-help] Maximum number of kernel tasks?

[Gilles Chanteperdrix]

Jefferson Noxon wrote:
> Hello,
> 
> This is my first project using Xenomai. I have a Diamond Systems Athena II
> board with an 800 MHz VIA Mark (Corefusion) chip. I built Xenomai 2.4.5 with
> Linux kernel 2.6.26.5 and I-pipe 2.0-09.
> 
> For some reason I can create 7 kernel tasks just fine, but the 8th task
> fails with -ENOMEM in rt_task_create(). I increased the heap size from 128Kb
> to 256Kb, but the problem persists. If I remove my kernel module and re-load
> it after a task creation fails, I get an oops in __xntimer_init after
> starting my first task (which is periodic).

This should be fix in xenomai 2.4.6.

> 
> If I build the same code to run in user-space (I have ifdefs allowing me to
> build it either way), I can create as many tasks as I want and my code
> behaves exactly as I would expect it to.
> 
> I imagine I am probably doing something stupid, but since it works in user
> mode I'm not sure what to check. Is there a limit of RT kernel tasks? If
> not, any pointers on how to debug this would be appreciated.

Did you try to change the stack pool setting in kernel configuration?

-- 
					    Gilles.

Re: [Xenomai-help] Maximum number of kernel tasks?

[Jefferson Noxon]

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On Sun, Nov 16, 2008 at 12:58 PM, Gilles Chanteperdrix <
gilles.chanteperdrix@xenomai.org> wrote:

> Jefferson Noxon wrote:
> > Hello,
> >
> > This is my first project using Xenomai. I have a Diamond Systems Athena
> II
> > board with an 800 MHz VIA Mark (Corefusion) chip. I built Xenomai 2.4.5
> with
> > Linux kernel 2.6.26.5 and I-pipe 2.0-09.
> >
> > For some reason I can create 7 kernel tasks just fine, but the 8th task
> > fails with -ENOMEM in rt_task_create(). I increased the heap size from
> 128Kb
> > to 256Kb, but the problem persists. If I remove my kernel module and
> re-load
> > it after a task creation fails, I get an oops in __xntimer_init after
> > starting my first task (which is periodic).
>
> This should be fix in xenomai 2.4.6.
>

Confirmed, thank you.


> >
> > If I build the same code to run in user-space (I have ifdefs allowing me
> to
> > build it either way), I can create as many tasks as I want and my code
> > behaves exactly as I would expect it to.
> >
> > I imagine I am probably doing something stupid, but since it works in
> user
> > mode I'm not sure what to check. Is there a limit of RT kernel tasks? If
> > not, any pointers on how to debug this would be appreciated.
>
> Did you try to change the stack pool setting in kernel configuration?
>
>
That fixed it. Thank you very much. Xenomai is incredible. I was worried
about a big learning curve, but I got up and running in almost no time.

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